Control system for a multiple speed power transmission



July 13; 1965 G. BOWEN ETAL CONTROL SYSTEM FOR A MULTIPLE SPEED POWER TRANSMISSION 5 Sheets-Sheet 1 Original Filed Oct. 29, 1958 July 13, 1955 G. 1 BOWEN ETAL.

CONTROL SYSTEM FOR A MULTIPLE SPEED POWER TRANSMISSION Original Filed Oct. 29, 1958 5 Sheets-Sheet 2 BY JUL/as ,40ml/ss, 4

July 13 1955 G. l.. BOWEN ETAL 3,194,373

CONTROL SYSTEM FOR A MULTIPLE SPEED POWER TRANSMISSION Original Filed Oct. 29, 1958 5 Sheets-Sheet 5 July 13, 1965 L G, L. BOWEN ETAL 3,194,373

CONTROL SYSTEM FOR A MULTIPLE SPEED POWER TRANSMISSION oxjiginal Filed Oct. 29, 1958 y 5 Sheets-Sheet 4 l2 Z 77a' INV ENT ORS P03527 14./ 5mn/ BY @cf/v A owf/v, 59

JUL /us A. (2,4 us5, n.

ATTO/PNE?? July 13 1965 G. L. BOWEN ETAL 3,194,373

CONTROL SYSTEM FOR A MULTIPLE SPEED POWER TRANSMISSION 5 Sheets-Sheet 5 Original Filed Oct. 29, 1958 qw .MNH

L bww www Qmw msm w mmh n. s Wwhm. www S. o 920W. GRAW f, S 53m. Nxt@ QM@ @5% SE d @Fmi WMM., um u QK O K @Sh 1 United States Patent O 6 Claims. (Cl. 192-37) This application forms a division of our application Serial No. 770,502, tiled October 29, 1958, now Patent No. 3,050,164, issued August 21, 1962.

Our invention relates generally to controls for a multiple speed ratio power transmission mechanism that are capable of conditioning the transmission mechanism for operation in any one of several speed ratios.

It is an object of our invention to provide a control system for use with a multiple speed ratio power transmission when a shift from one ratio to another can be accomplished while the transmission is delivering power merely by disengaging one coupling member and engaging another in sequence.

It is another object of our invention to provide controls for a multiple speed power transmission mechanism having dual power delivery path, each path being capable of providing multiple torque ratios, wherein one path can be conditioned for torque delivery while the total power is being transferred through the other and wherein the other path can be conditioned for torque delivery at another ratio while the total power is being transferred through the one path.

It is a further object of our inventio-n to provide a vehicle transmission control system that comprises a pair of steering clutches and a steering brake at each of two power output members wherein the degree of engagement of the clutches and brakes can be varied to permit turning maneuvers of the vehicle at various turning radii. Further objects and features of our invention will become apparent from the following description and from the accompanying drawings wherein:

FIG. 1 is a cross sectional assembly view of our improved transmission structure;

FIG. 2 is a rear end view, partly in section, showing a portion of the steering mechanism associated with transmission structure of FIG. 1

FIG. 3 is a cross sectional assembly View of a driving connection between the fluid coupling of the assembly of FIG. l and the main power input shaft for the main gear assembly;

FIGS. 4 and 4a show a schematic representation of the transmission control system and the associated controls for the clutch-brake and geared steering components.

Referring first to FIG. 1, the main gear assembly is generally identified by numeral 10, a fluid coupling is generally designated by numeral 12, low range steering clutches are generally designated by the numerals 14 and 16 and high range steering clutches are generally designated by numerals 18 and 20.

By preference, the transmission structure may be mounted in a vehicle with the axis of the clutches 14, 16, 18 and 20 disposed transversely with respect to the center line of the Ivehicle and with the iiuid coupling 12 disposed in a forward location in driving relationship with an engine driven drive shaft. In such an arrangement, low speed range clutches 14 `and 16 may be adapted to be selectively clutched to power absorbing members such as the vehicle traction wheels or tracks, and the clutches 1S and 20 may be similarly adapted to form a driving con- ICC nection for operation in a relatively high speed range. The manner in which power is transferred from the engine through the coupling 12 and through the gear assembly 10 to the lower and high range clutches will become apparent from the following description.

Particular description of transmission assembly rl`he main gear assembly 10 is disposed within a main transmission housing identified by the numeral 22, and auxiliary housings are situated on either side of the housing 22 as shown at 24 and 26, the housing 24 enclosing clutches 14 and 18 and the housing 26 enclosing clutches 16 and 20. The fluid coupling 12 is enclosed by a suitable housing 28 as indicated.

An engine driven drive shaft is represented in FIG. 1 at 30 and it is drivably connected to a hub 32 which forms a part of a hydrokinetic pump member 34. The hub 32 includes an adapter 36 extending axially with respect to the pump member 34 and it is journalled in a roller bearing assembly 3S. Bearing assembly 38 is disposed in a recess formed -in a hub 40 for a hydrokinetic turbine member 42 of coupling 12. Adapter 38 is also concentrically disposed about a power delivery shaft 44, and one end of the shaft 44 is journalled by means of a bearing 46 in a pilot opening formed in the end of the drive shaft 30.

The pump member 34 and the turbine member 32 are each provided with a plurality of ow directing vanes disposed in juxtaposed relationship and the vanes of each member are confined in a cooperating outer shroud, the latter dening the boundaries of a toroidal fluid liow circuit.

The pump member 34 may be drivably connected to a power input drive shaft 30 by suitable bolts 48 which extend through hub 32 and the associated adapter 36. Additional support may be provided by a pump shell 50 which is secured to the outer periphery of the shroud for the pumping member 34 by suitable bolts 52, the pump shroud and the pump shell 50 being provided with suitable peripheral anges for this purpose. A radially inward extremity of the pump shell 50 is connected to a bearing member 54 which in turn is journalled on a cooperating extension of the hub 40 of turbine member 42. The hub portion on which the bearing member 54 is journalled is in the form of an adapter which may be positively secured to turbine member 42 in a suit-able fashion, such as by dowel pins or bolts, and which may be splined at 56 to provide a driving connection between the pump member 42 and the shaft 44, the shaft 44 being externally splined for this purpose.

The main housing 22 may be formed with a central aperture and a bearing retaining member 56 may be permanently situated therein as indicated. A ball bearing 5S is retained in bearing retaining member 56 for the purpose of journalling shaft 44. The end of shaft 44 is externally splined at 60 nand an internally splined driving gear 62 is drivably carried on the end of shaft 44. A retainer 64 in the form of a washer ris secured to the end of the shaft 44 by a bolt 66 in order to retain the gear 62 in place.

If desired, bearing member 44 may be formed with external gear teeth and an auxiliary driving gear 68 may be journalled in a suitable adapter 70 fixed in one portion of the housing 22. Gear 68 may be disposed in driving relationship with respect to a gear 72 which in turn may be utiiized as an engine accessory drive or for driving an engine driven tluid pump for obtaining the control pressure necessary for use in energizing transmission control system. Also the above mentioned peripheral flange on the pump shell 50 may be utilized for the purpose of mounting an engine starter ring gear 74 in a conventional fashion.

Referring next to FIG. 3, we have illustrated in diateeth 262. A positive driving connection is therefore established between power input gear 172 and power output shaft 118, the torque delivery path being defined by gear 170, gear 174, sleeve shaft 138 and clutch disc assembly 186 and A192, `counter shaft 126, -synchronizer clutch element 198, gear 261i and gear 284.

Gear l172, which is journalled about the axis of output shaft 118, is in driving engagement with gear 144 journalled for rotation about shaft 122. Sleeve shaft 140 is formed with a radial fiange 208 which partly defines an annular cylinder 210 within which an annular piston 212 is slidably situated. A clutch member 214 is carried by the radially outward portion of flange 218 and it is internally splined to accommodate a driving connection with external splined clutch discs 216. Member 214 also has secured thereto a clutch disc back-up member 218. Cooperating clutch discs are identified by numeral 220 and they are internally splined to accommodate a driving connection with clutch member 222, the latter being positively connected to counter shaft 122 by means of a spline connection 224. It is thus apparent that when fluid pressure is admitted to the chamber defined by cylinder 210 and cooperating annular piston 212, the clutch discs 216 and 220 will be brought into frictional engagement thereby establishing a driving connection between gear 144 and counter shaft 122.

An intermediate portion 226 of counter shaft 122 is externally splined as indicated at 228 to accommodate a driving connection with a synchronizer clutch member 230. The clutch member 230 may be adjusted axially with respect to counter shaft 122 although the connection provided by spline 228 prevents relative rotation thereof with respect to counter shaft 122.

A gear 232 is rotatably journalled on counter shaft 122 by suitable bushings, and it is formed with an extension having external clutch teeth 234 disposed adjacent the splined counter shaft portion 226. When clutch element 230 yis adjusted in a left hand direction, as viewed in FIG. 1,*it will drivably engage clutch teeth 234 to establish a positive driving connection between counter shaft 122 and gear 232.

During operation of the transmission structure in a socalled second speed ratio, the clutch disc assembly 216 and 220 is engaged and the clutch element 230 is shifted in a left hand direction, as viewed in FIG. 1, to couple gear 232 with counter shaft 122. A torque delivery path between power finput gear 144 and power output shaft 118 is therefore defined by sleeve shaft 140, the clutch disc assembly 216 and 220, counter shaft 122, clutch element 236, gear 232 and gear 2114.

An externally splined clutch element 236 is mounted on counter shaft 120 in concentric relationship therewith and is positively connected thereto by means of a spline connection. A shiftable clutch element 246 is situated in engaged relationship with respect to clutch element 236 and it is formed with internal spline teeth which cooperate with external spline teeth on the element 236. Clutch 240 may be adjusted axially with respect to counter shaft 120, and when it is moved in a right hand direction, as viewed in FIG. l, it drivably engages external clutch teeth 242 formed on the hub of a gear 244, the latter being rotatably journalled on counter shaft 128 by means of suitable bushings as indicated. Gear 244 is disposed in driving engagement with a gear 246 which in turn is positively connected to output shaft 118 by means of a suitable spline connection 248.

During operation of the transmission in the third speed ratio the clutch disc assembly 186 and 192 may be energized and the clutch element 24@ may be shifted in a right hand direction, as Viewed in FIG. l, to effect a driv.

ing connection between counter shaft and the gear 244. rEhe clutch disc assembly 216 and 221B will be released during operation in the third speed ratio. A power delivery path between power input gear 172 and the power output shaft is therefore defined by gear 171B, gear 174, sleeve shaft 138, clutch disc assembly 186 and 192, counter shaft 126, clutch elements 236 and 246 and gears 244 and 246.

A gear 251i is rotatably journalled on counter shaft 122 by means of suitable bushings and the hub thereof tis formed with external clutch teeth 252. A spline clutch element 254 is situated adjacent gear 250 and is positively connected to counter shaft 122 by means of a spline connection 256. Another internally splined clutch element 258 is carried by clutch element 254, the latter having external splines which cooperate with the internal splines of clutch element 258 to permit relative axial adjustment of the latter. When clutch element 258 is adjusted in a right hand direction, as viewed in FIG. 1, the internal clutch teeth thereof engage clutch teeth 252 to establish a positive driving connection between gear 256 and counter shaft 122.

During operation in the fourth speed ratio, clutch disc assembly 216 and 226 is applied and clutch disc assembly 186 and 192 is released, and a power iiow path between the power input gear 172 and power output shaft 118 is therefore defined by gear 176, gear 144, sleeve shaft 148, clutch disc assembly 216 and 220, counter shaft 122, clutch elements 254 and 258, gear 250 and gear 246.

A gear 261i is rotatably mounted by means of suitable bushings on counter shaft 120 adjacent clutch element 236 as indicated. The gears 260 and 244, the clutch element 236 and the gear 266 are disposed in axially stacked relationship between the intermediate portion 1% of counter shaft 120 and the bearing adapter 126 with suitable thrust washers therebetween. Axial displacement of these members relative to counter shaft 120 is therefore prevented.

The hub of gear 260 is also formed with external clutch teeth 262 which may be engaged by the internal spline teeth of clutch element 240 when the element 240 is shifted in a left hand direction, as viewed in FIG. l. When the element 241) is shifted in this fashion, a direct drive connection is established between the gear 26) and counter shaft 120. The gear 260 is in driving engagement with a gear 264 formed on power output shaft 118.

During operation in the fifth speed ratio, the clutch element 241B assumes a left hand position and clutch disc assembly 216 and 220 is released while clutch disc assembly 186 and 192 is applied. The torque delivery path between power input gear 179 and the power output shaft 118 during operation in the fifth speed ratio tis defined by gear 170, gear 174, sleeve shaft 138, clutch disc assembly 186 and 192, counter shaft 120, clutch elements 236 and 240 and gears 260 and 264.

A gear 266 is rotatably journalled on counter shaft 122 by suitable bushings and the hub thereof is also formed with external clutch teeth 268. The teeth 268 are adapted to be drivably engaged by the internal spline teeth on clutch element 258 when the clutch element 258 is'adjusted in a left hand direction. This establishes a direct driving connection between gear 266 and counter shaft 1212. The gears 232 and 250, the clutch element 254 and gear 256 are situated in axially stacked relationship `between intermediate portion 226 of counter shaft 122 and bearing adapter .130 and suitable thrust washers may be provld'ed between these members as indicated.

Durmg operation in the sixth speed ratio, clutch element 258 is shifted in a left hand direction as viewed in FIG. 1 and clutch disc assembly 186 and 192 is released while clutch disc assembly 216 and 220 is applied. The torque delivery path between power input gear and the power output shaft 118 during operation in the sixth speed rat1o is defined by gear 172, gear 144, sleeve lshaft 141i, clutch disc assembly 216 and 228, counter shaft 122 clutch elements 254 and 258, gear 266 and gear 264.

As previously indicated, agear V148 is secured toV one en d Vof poweroutput shaft MS, and. this gear 148 1s sit- 1 uated in driving engagementfwitha gear 27@ which is ro-.v

.tatably `mountedon a bearing adapter 272by means of a Y rollerrbearing 274.' BearingV adapter-272 is in turn setnerright end ofcounter shaft 120.

A drum-shaped clutch member, 276 is secured to gear- 279 by means of bolts 27S and it is adapted to rotate con-1V jointly therewith. The Vradially inward Y end of. clutch memberV 276 is piloted within the bearing adapterV 272.

A supporting shaft 280 iis received; withinthe bearing adapter 272m coaxial relationship with respect to counter shaft 12) and it alsoextends through a gear-282' situ- Y ated v`on the right side of the main transmission gear assernbly.V Suitable needle bearings are provided, as shown at, 284 and` 286,10 accommodate relative rotation ,be-

tween gear 282 and`shaft1280, and the gear 282 is in turn supported by a roller bearing 283. Bearings 288 are received within bearing openings formed in an end vplate 291? which forms Va part of housingiZd. A suitable cap 232 `can be provided if desired for'the purpose of coveringthe bearing 28S.

A clutch member 294 iszintegrally j oinedto gear 232 and is externally splined so that cooperating internally Y splined clutch discs 296 can be carried thereon.

The clutch member 276'includes an outer peripheral portion 29Swhich is internally splined so that externally splined clutch discs 3G@ canv be .carried thereby, Vand aV clutch disc backup Vmember is carried by the peripheral portion 298 as shown at 392. v

The clutch member 276 andthe shaft lrcooperate to y deinean annular working cylinderM within whichan annulanpiston 306v is slidably situated. When iluidpressure is admitted into the cylinder 394 the clutch discs 296' and Stilly areurgedinto frictional engagement, thereby es# ,Y

tabllishin'g a driving connection between gear 27d-and gear 282. Piston34 is urged toward a retracted positron byV meansof a pistonreturn spring y3dS whichis 2te seated on `a spring seat member 310. v Seat member-31! Y may in turn be vanchored against a cooperating shimlderA formed o n shaft 28d. The clutchmember 270 mayk be suitably keyed or otherwise secured to the shaft'ZiB 1in the vicinity of the bearing adapter 272, and the end of i shaft 28@ may be threaded to accommodate a loching nut If desired, a ball check pressure relief,valve 314 may be.A

provided .in vclutch member276 ata radially ,outward location in rorder to prevent a buildup in' centrifugal pressure within the cylinder 304 when the low speed Asteering clutch 14is released. This valve also provides a` rapid exhaust of fluidV from the cylinder 364 when release of the clutch 14-is initiated.YV

Gear 148 is also in driving engagement with 1a gear 316 which in turn'is mounted on a bearing' adapter 318 by means of aroller bearing 320. The high Vspeed steering clutch 18 is similar in construction to the above described low speed steering clutch 14 and it includes a drum-shaped clutch ,member y322 secured to gear 316 by bolts324 for conjoint movement therewith. A supporting shaft, similiar to the previously described shaft 281),'is provided at 324 anda gear 326 is mounted aboutshaft 324. Gear 32o-.is rotatably journalled by means of ka roller bearing 328,.,and bearing 328 isin turn `secured within a suitable bearing aperture formedY iny end plate 2926;' A suitable cover or cap 33) may be used for covering bearing 328,.=

- Bearings 332 andV 334 may be used to accommodate relative rotation between gearf326 and shaft 324.: A

can be'carried thereby; Clutch member 332Ymay be in-v ternally splined to accommodatefa connection with ex- VGO ternally splined clutch discs 340. Thevclutch member 322 and shaft 324 cooperate to define an annular cylinder SAEZ-within whichan annular` p' ton 344 .is slidablyfsitu. ated.v Whenifluid pressure isadmitted into the cylinder I 342.7 thepistonddA urges the clutch discs. 33.8yand 340 into .frictional engagement to establisha drivingV connection betweenY gears 3716 rand 326. e

16 and 20 are identified ,inlFIGQlby primed `reference numeralswhich correspond to those members-*which form a counterpartthereof in steering lu'tches114i'and"18.v The power deliveredtoV gear/146 layshaft llfjistherefore y Ytransmitted directly to .eitherv of, the gears 4 2 7 0'-r and 3164.

When the multiple clutch'd-iscassembly forlsteering clutch' 16,V is applied, a driving connection is establishedbe-.-

tween gear Y27d and gear 2821; andin asimilar fashions when the multipleclutch fdiscasser'nbly for thehighA speed"Y Y steering clutch V20 is feriergized,v adriving'connectionds established between gear, 31.6".and`gear 326'."Y The manlzg ner in which thevar-ious highspced and low-speeds'teer'ing Y' clutches areV applied andthe .operatingf-sequencejthereof i willfbecorne,l apparent from the subsequentidescription;Of-

the control-system asy illustrated in FIGSQ Aand 4a.

Referring next to `Jr-"IGjZNi/e.have `-illustrated, a power output gearat v346,:and `it is formedwith anY elongated hub 48 which is rotatably supportedby spaced rollerI bearings.

35h and 352. Bearings'350.and` 352 areinrturn Vposis tioned withinsuitablebearing` apertures Eformed in. end

wall 290'; of housing 26 and in-a Vhousing portionf3541!..y

The hub 348 is internally splinedand ispositively engaged withV .an externally splined power?` output member 356'.' l

The member 356 is formed with.-a radially :extending-:disc f portion 358 whichinturn :is externallypplined-'as shown atdl tofacilitate a driving connection rwith a brake disc v 362. e Apower delivery connection between member 356 andthe vehicle tractionwheels or tracks maybe Vformed i in any suitable manner; andfif desired, ianlinter/in 'ediate f iinalJdrive 'mechanism may be employed-fo. provide an additionalY torque multiplication lfo r*additionz il tractive e' brake housing 376 suitably secured ito end plate 2%v by bolts 37S, the housing 376 being ,suitab lyV Vhanged to';

facilitate such laconnection. The*housing' 376" is vformed j 'witha transverse openingilwithin which brakedisc362-j is received, y as will be subsequently explained withrefer- I Y ence tothe schematicdrawings of FIGS. 4 and `4a.

The-brake assembly Vl-"includes a fluid pressure operated brake piston shown in part in LFIG. ljat382. 'Theav brake `'assembly 374 further includes a frictionmember 34 ysituated. adjacent. one sideofv thebrake disc 362.' When `the' brakeassembly 374i' is pressurized,lpiston,3 82 E7 is urged into frictionallengage/ment withfbrake disc362f and abrakingeffort is thusrapplied V to brake disc 362.;` f A portion of the fluidpressurepassage which is used for Y Y pressurizingthe Vilud'pressure working chamberofthe brake assembly 374'lisshown in FIG. 2 :at 386;:` '..Thispa'ssage` 386 forms a portion'of -thelfcontrol-systemwhich will be described with reference to FIGS.` 4 and 402.-?

9 is received therein. The brake assembly 388 also includes a pressure operated piston which is adapted to exert a frictional braking force on brake disc 362 in a fashion similar to the operation of brake assembly 374.

A second pair of disc brake assemblies are situated on the right side of the transmission assembly, as viewed in FIG. 2, and these brake assemblies are identified by the numerals 392 and 394. A brake disc is shown at 396 and it acts in cooperation with the brake assemblies 392 and 394 in the manner previously described. The brake disc 396 is positively connected to a power output gear (not shown) which is similar in function to power output gear 346 and mounted in driving engagement with gears 326 and 282.

Referring again to FIG. 1, the splined clutch elements 236 and 240 form a portion of a synchronizer assembly which provides synchronized engagement between clutch member 240 and either one or the other of the gears 260 or 244. The synchronizer assembly includes a plurality of blocker shafts 398, each shaft 293 being situated within a cooperating opening formed in clutch element 240. The ends of each shafthave secured thereto cone clutch members 4110 and 462 which are adapted to 'cooperate with cone clutch surfaces formed on gears 260 and 244, respectively. When the clutch element 240 is in the intermediate or. neutral position, as shown in PIG. 1, clearance exists between shafts 398 the cooperating openings formed in the element 240. y

When it is desired to couple gear 260 with counter shaft 120 -under those conditions in which a speed differential exists therebetween, the clutch element 240 may be urged in a left hand direction as Viewed in FIG. 1. A blocker shoulder on shaft 398 will then be brought into engagement with a cooperating shoulder formed on the clutch element 240. The shifting force which is applied to the clutch element 240 will therefore be transferred through shaft 398 to clutch member 400, thereby causing a clutching engagement with gear 260. The rotary motion of gear 269 will therefore be transferred through the synchronizer assembly to counter shaft 120 thereby causing the latter to accelerate. After the counter shaft 120 and the gear 260 assume a synchronous speed, clutching engagement between clutch member 240 and clutch teeth 262 will become feasible and the shafts 398 will become centered in the cooperating openings formed in clutch member 240 so that the cooperating blocker shoulders on the shafts 39S and the clutch element 240 will no longer engage each other. The clutch element 240 may then be shifted to its left hand position into engagement with clutch teeth 262. The synchronizer assembly thereby eliminates a clashing of the clutch teeth.

In a similar fashion when clutch element 240 is shifted in a right hand direction to effect third speed operation, the counter shaft 120 may be brought into synchronism with respect to gear 244 before the clutch element 240 drivably engages the clutch teeth 242. In this case a second blocker shoulder formed on shafts 398 prevents movement of the clutch element 240 in a right hand direction when the shafts 398 are misaligned with respect to the cooperating openings due to a difference in the speeds of rotation of counter shaft 129 and gear 244. The lshifting effort applied to clutch element 241i is transmitted through shafts 398 to clutch member 492, and when a synchronous speed is obtained, the shafts 39S will permit the clutch element 240 to be moved to its extreme right hand position.

A similar double acting synchronizer assembly is provided for gears 266 and 250 to effect a synchronized shift to condition the transmission for either sixth speed operation or fourth speed operation. Similarly, a single acting synchronizer assembly is provided for gears )V and 232 to provide a synchronized driving connection between counter shaft 120 and gear 200 and between counter shaft 122 and gear 232 when the transmission is condil@ tioned for first speed operation or second speed operation, respectively.

Operation of the transmission structure of FIG. 1

To obtain first gear operation, the gear 290 is clutched to counter shaft as previously explained, and the clutch disc assembly 186 and 192 is applied. Torque is then delivered through gears and 174, through clutch disc assembly 186 and 192, through counter shaft 12d and through gears 201B land 204 to the power output shaft 118. When it is desired to condition the transmission for second speed operation, gear 232 may be clutched to counter shaft 122 while power is still being delivered through counter shaft 120. In order to complete the transition from first speed operation to second speed operation it is then merely necessary to disengage clutch disc assembly 186 and 192 and to conjointly apply clutch disc assembly 216 and 220. The control system hereinafter described is arranged so that a desired amount of overlap may be obtained during the disengagement of clutch disc assembly 186 and 192 and the application of clutch disc assembly 216 and 220, and a smooth transition from the first speed ratio to the second speed ratio is thus accomplished without an interruption in the power delivery to the output shaft.l The torque delivery path during operation in second speedis thus defined by gear 172, clutch disc assembly 216 and 220, counter shaft 122 and the gears 232 and 294, and no power is transferred through counter shaft 120.

When a shift from the second speed ratio to the third speed ratio is desired, gear 244 may be clutched to counter shaft 12) by its associated spline cl-utch while power is beingtransferred through counter shaft 122. In 4order t0 complete the transition from second speed operation to third speed operation, it is merely necessary to disengage clutch disc assembly 216 and 220 and to conjointly engage clutch disc assembly 186 and 192. Again, the control system is capable of sequentially operating the clutch disc assemblies for the respective counter shafts to provide a smooth transition from one speed ratio to another without any interruption in the power delivery path.

In a similar fashion the transmission may be conditioned for fourth speed operation by clutching the gear 250 to counter shaft 122 by means of its associated spline clutch while power is being delivered through the counter shaft 120. The transition from third speed ratio to fourth speed ratio may then be completed by sequentially disengaging the clutch disc assembly for counter'shaft 120 and applying the clutch disc assembly for counter shaft 122. It is thus apparent that counter shaft 120 no longer forms a part of the power delivery path during operation in the fourth speed ratio.

In order to initiate a shift from fourth speed ratio to fifth speed ratio, gear 260 is clutched to counter shaft 121) as previously described while counter shaft 122 is still in the power delivery path. The clutch disc assembly for counter shaft 120 is then applied in sequence with the disengagement of the clutch disc assembly for counter shaft 122. After the shift is completed, counter shaft 122 no longer forms a portion of the power delivery path.

A shift from fifth speed ratio to the sixth speed ratio may be accomplished by clutching gear 266 to counter shaft 122 while power is being delivered through counter shaft 121i. The clutch disc assemblies for countershafts 122 and 120 may then be sequentially applied and released, respectively, in the manner previously described.

During the above described sequence it is necessary to release the first speed synchronizer assembly before the third speed synchronizer assembly is actuated since both synchronizers cannot be simultaneously engaged. In a similar fashion the third speed synchronizer must be disengaged at a time prior to the engagement of the fifth speed synchronizer.

Since two of the synchronizers associated with counter shaft 122 cannot be applied simultaneously, provision is provision is also made for disengaging the fourth speed syn-J chronizer prior to thezengagement of the sixth speed synchronizer.

During operation of the transmission mechanism in the forward drive rangeas above described, power is delivered from the fluid coupling 12 to the power input geargl70 through theV geared power flow path defined by gears 62,' 76, S6, S3 and 164. The synchronizer clutch element 100,

connection between shaft 96 and bevel gear 88'. Thesynchronizer mechanismassociated with gears 83 and 90 ris `10f `as shown in FIG. 3, in this instance establishes a driving` similar inconstr-uction and operation to theV synchronizer mechanism for gears 26@ and244 which wasv previously described. Y

In order to conditionthe transmission mechanism forA reverse drive operation, the synchronizer clutch element i' 1b@ may beshifted in aleft hand Vdirectionas viewed in drive possible.

In the presently describedfembodiment of our invention a i the control system is adapted to cause application ofthe low speed steering clutches14rand 16 during operationin' v reverse and in the firstV and second speed ratioswhile:

simultaneously disengaging the high speed steering clutches 18 and k2t). The overallttorque multiplication ratio durf ing operation Vinireverse and in the rst and second speed operation in the third, fourth, fifth and sixth' speed ratios,

the lowspeed steering clutches 14 and 1 6 are released and"l the'high speed steering clutches 18 and Ztlareapplied.

ln this preferred embodiment, above described, Vwe Y t have obtained an overall 'torque,multiplication*ratiolduri Y ing Iirst speed-operation of 15.029,:'1and `the r'atiofor, The'` ratios for second,y third, fourth and iifthspeed operation sixth speed ratiois an overdrive ratio ofV .9578:1',

are, respectively, 9.215:l, `4.12441,2.5.2911,.and1.55921. If `the transmission structure is used', in combination with a kfinal drive mechanism, ythe gear ratio of -the final drive z '30` ratios 1s therefore at a maximum value. However, durlng, f

its?

tionand the .checlrvalve V4201 will'a'ssurn'e aA closed .posie i Y tion, and: pressure regulation will take placeinthe man-v ner. previously described However, when'the dischargeA pressure for the, pumpdexceeds the discharge pressure Y y for' the pump 404, the checkvvalve Zd-willfheopened andV y Y the kcheclr'valve 4178gwill be closed. Passage dticommunicates fwithy ,theregulatorfzvalve ,chamberf at ,al lorca; tion adjacent valve landAZZ, andgi'theL-degreewo'f :com-r` Y Vmunication betweenpassage 468 and passagej412 is fconflr f trolle'd by` land 42(2ffUnde1 these.,- conditions, f-'the fluid, i pressure force. acting on valVeplungerf41'6 andthe ops t posing spring force ,acting-on-valveV spoolifzltl .become 1 rearranged so' ,that the valve-'land ,422.will'assume' a Vpressure regulating-position. Y The pump 366Will' then supply theentire pressureprequirernents of thejcontrol system,v and the pump y45194 will communicatevdire'ctly with-the ex-VY haust Ypassage '.412 since vvalve .land v4,14 j will `provide free.v communication between the high pressureand lowpressurev sides `of pump- 4.04.whenthe:valve-element,41)-as.v

sumes this new regulating VV(position.

The; regulatorvalve 406 isgalsoycapable offcontrolling the distribution of fluid u'pressure'.to,v thefuid coupling- 12,; a valve landg424fbeing provided for this purpose; e. A. fluid pressure` passage I,extendingtothefiiuid .couplingilZjri j Y uncovered Y`by valve land j424i afterY ythe,valvespoolfli-1t), assumeseits normali .regi-1112iting'Y positiornYA The' regulator- ,t valve 406 `tliereforefoperates-1t`o,supply'thecontrol systemu with full Y control ,pressureA ,before it allowsfluid,pressureYK to ,be'distributed ,to the fluidi coupling. `Thisfeatureisrk Y desirable 'sinceathe,transmissionclutches,,willbercapable Y Vof, assuming y ,their full; torque transmitting; capaeitieslbemechanism would provide a further, overall torque Vmulti- -Y plication for each speedl ratio; y

` Description ofconnolcircuif10fFIGs-4 and 4a which iscornrnon to, both pumps 404,and 366:vr

, The regulatorvalvetdo is located on the discharge-V side of the pumpfand it includes a multiple land valve spool 410 which-is situated in a cooperating valve chamber and urged in aleft hand direction, as viewed in FiG.

4, by an associated valve spring.A A low pressure fluid exhaust passage is shown at 412 andavalve land 414 1 is adapted'to control the degree of communication ,betweenV the discharge side of the pump 404 and passage 412. A

valve plunger 416is situatedV in regulator valve 4% so` Y that itrcontacts thevalve'spool 410, and one side thereofis subjected to the control pressure existing in'pass'age` ItV is thus apparent thaty the spring force of the ;V regulator valve spring willV oppose and balance the -i'luidV` pressure force applied to the valve plunger 46h, Vand the effectve discharge pressure of pump 464 will be regulated at a calibrated maximumfvalue.

Y A one 'way check valve 41S, is ,provided on the disf charge side ofV pump 404, and a similar one way checlrvalve 420 is provided Von thexdischarge Vside of the'output shaft driven pump 366. When Vthe dischargerpres- Y sure of the .pump 464 exceeds the 'discharge pressure for pump 356, thecheck valve 418 will assumey an open posiforepfull enginetorque cangbe yapplied to; thepg'wer input.;

membersof the gear. assembly. f

Fluidppressure"isdistributed from; passageiitilto 'Y manual valve through passage l42:6,2the .manualvalve be! ingV idelntiiiedfinFlGrA- by numeral 34H3..v The manual" valvej 428"'includes a multiple landfvalve .spoolv sli'dablfy disposed in Va cooperating,valve'fch'amberrandgit"includes four' spaced .valveflands which fare identified,in,FYIG. 2lV by.

tsbleiEmechaDQaI. Y linkagernchanisrn,generallyiidentiy ed byjnumer'al ,43.8, e. Y' may be employed vrfor` adjustingtlie,positionfofvalve ,spoelt .428 to ,anyofV several operating positions dependingupon;

the speed ratiowhichlisidesired. vj,The`individualoperatin l' positions ofthe valve spool 428finay1be defined ,b'ya'r sui able spring Adetent'asfshown at 1405., Thegrnanual valve.` is` shown vin`v FIGA; 4:in.,they'positiorr"eorrespendings,.torH

" neutral, and 4f det'entj recesses..-are formedjin theinanualV valve at evenly spaced locationswhich( correspond' to the'.-

used to identify eachlof vthe six speedf ratio` positions. An :internal passagexis Vformediin` valve'spool'zrasf j i shown at 412.21y for thepurpose ofestablishing eomrnunicafiV tion between Vthe annular. valve spacedeiined by'valve Y.

VVlands ,430 y.and 432 and thejannular space :defined V.by j L Y valveV lands 434jand'1436- E Theprincipal" cor'nponentsV ofY the controlVv systemV of FIGS.V 'K4`and 4a which f are' utilized;

for theppurrposeo'f Ycontrolling'thesequentialfshifts, asi? Y Y above fdescribed; includeV a iirstfspeed synchrbnizerV vservo 444, a second speed synchroniser.;servorldfathird and 'g 1 fth speed` synchroni'zerfservo- ,44:88 .and a'fourth Landy-sixtlrV speed `synchroniser servo 215th,V t Inaddition, Y a iirstl ,clutchY w transition valve is VshownV at` 452'Iwhich Vis effective to'con" trol the distribution offluid pressure `to; thel.multipleVV clutchzdiscassernbly V185fand- 192.?v Forgpin'poses.` of

' convenience'this clutch disc,assembly-willV hereinafter Vbe Y referred to as the C1 clutch :and the transitionvalve-45211; v

associated'therewith will'berefe'rred to as` theCl transition of convenience the clutch diseassembly*Z116` -andZZtgwill hereinafter be referred to asthe C2 clutchvandf the transitionvalve `454. associated AtherewisthY'will be. :referred to` `as the C2 transition valve.. Y Y

In addition, we have provided a so called low range valve as shown at 456 for controlling the distribution of fluid pressure to the high steering clutch and the low steering clutch located on the right side of the transmission assembly as viewed in FIG. l, and a similar low range valve is provided at 458 for controlling the distribution of liuid pressure to the corresponding steering clutches on the other side of the transmission assembly.

The first speed synchronizer servo 444 comprises a piston member 460 having a pair of spaced annular valve lands as shown at 462 and 464. The piston 4&0 is mounted within a cooperating cylinder and defines therewith a pair of opposed working chambers illustrated in FIG. 4a on the upper and lower sides of the piston 46),

' respectively. The piston 460 is mounted within a cooperating cylinder and defines therewith a pair of opposed working chambers illustrated in FIG. 4a on the upper and lower sides of the piston 45t). The piston 460 may be mechanically connected by a suitable actuator rod 466 to a shifter fork which is adapted to engage the clutch element 198 of the first speed synchronizer when the piston 464i is urged in an upward direction, as viewed in FIG.,4a. The clutch element 198 is shifted into clutching engagement with clutch teeth 202 to establish a driving connection between counter shaft 12? and gear 200. The piston 460 is urged in a downward direction, as viewed in FIG. 4a, by a synchronizer servo spring.

The second speed synchronizer servo 466 is similar in construction to the first speed synchronizer servo 444 and it comprises a servo piston 470 situated in a cooperating servo cylinder to define a pair of opposed fluid pressure working chambers, said chambers being illustrated on the upper and lower sidesof the piston 47? as viewed in FIG. 4. A pair of annular valve lands 472 and 474 is formed on the piston 470 and these valve lands correspond to the aforementioned valve lands 462 and 464 of the first speed synchronizer servo piston 469. The piston 470 is positively connected to a shifter fork 476 by means of an actuator rod 478, and the shifter fork in turn is adapted to move the aforementioned synchronizer clutch element 235) into and out of engagement with clutch teeth 234 whereby the gear 232 is selectively clutched to and declutched from counter shaft 22. The piston 470 is normally biased in a downward direction, as viewed in FIG. 4, so that clutch element 230 normally assurnes a declutched position. However, when iuid pressure is admitted to the fluid pressure chamber on the lower side of the piston 470, the clutch element 230 is shifted into engagement with clutch teeth 234.

The third and fifth speed synchronizer servo 443 comprises a double acting piston 480 which cooperates with a servo cylinderto define a pair of opposed fluid pressure chambers on either side of the piston 48d. A pair of synchronizer servo springs is provided for normally biasing the piston 480 toward a central neutral position. A pair of spaced valve lands is formed'on piston 480 as shown at 482 and 484. The piston 486 is positively connected to a shifter fork 485 by means of an actuator rod 488 and the shifter fork 486 is in turn situated in engaged relationship with respect to clutch element 240 associated with gears 260 and 244. When fluid pressure is admitted to the lower side of the piston 430, the clutch element 240 will be shifted into engagement with clutch teeth 262 thereby coupling gear 260 to counter shaft 120, and when fluid pressure is admitted to the upperside of the piston 480 while the lower side thereof is exhausted, the clutch element 240 will engage clutch teeth 242 thereby coupling gear 244 to counter shaft 120.

The fourth and sixth speed synchronizer servo 450 is similar in form to the third and fifth speed synchronizer servo and it includes a double acting piston 490 on which is formed a pair of spaced valve lands 492 and 494. The piston 490 is likewise normally biased toward an intermediate neutral position by synchronizer servo springs as indicated.

The piston 490 is positively connected to a shifter fork 4% by means of actuator rod 49S, and the shifter fork 4% is in turn situated in engaged relationship with respect to clutchelement 258 associated with gears 266 and 250. When fluid pressure is admitted to the fourth and sixth speed synchronizer servo 45t) on the lower side of piston 49@ while the pressure chamber on the upper side thereof is exhausted, the clutch element 258 will establish a positive driving connection between gear 266 and counter shaft 122. However, when fluid pressure is admitted to the pressure chamber on the upper side of the piston 490 while the pressure chamber on the lower side thereof is exhausted, the clutch element 253 will establish a positive driving connection between gear 250 and counter shaft 122.

The C1 transition valve 452 comprises a valve spool 560 having a pair of spaced valve lands 5tl2 and 504. Also the C1 transition valve includes a valve element 536 situated in the valve chamber occupied by valve spool 500. The C1 transition valve is adapted to control the distribution of fluid pressure to the C1 clutch in a manner hereinafter described, and itis normally biased in a right hand direction, as viewed in FIG. 4a, by a C1 transition valve spring.

The C2 transition valve is similar in construction to the above described C1 valve and includes a valve spool 508 having a pair of spaced valve lands 510 and512. Also a Valve element5l4 is situated in the valve chamber occupied by valve spool 508 and a synchronizer servo spring is provided as indicated for normally biasing the valve spool 508 in a left hand direction, as viewed in FIG. 4. The C2 transition valve functions to control the distribution of iiuid pressure to the C2 clutch in a manner which will hereinafter be described.

The low range valve 456 comprises a valve spool 516 having three spaced valve lands 518, 520 and 522. Valve spool 516 is normally urged in an upward direction, as viewed in FIG. 4a, by a low range valve spring and a fluid pressure chamber is formed on the upper side of valve spool 516 within the cooperating valve chamber in which valve spool 516 Ais situated. As previously mentioned, the low range valve 456 is adapted to control the distribution of control pressure to the high and low speed steering clutches, and it is also effective to control the distribution of a modulated tiuid pressure to the disc brake assemblies 392 and 394. However, for purposes of convenience, only the disc brake assembly 392 has been illustrated in FIG. 4a.

The low range valve 458 is similar in form to the above described valve 456 and it comprises a valve spool 524 having three spaced valve lands 526, 528 and 530. Valve spool 524 is normally urged in an upward direction, as viewed in FIG. 4, by a low range valve spring and a uid pressure chamber is defined by the valve spool 524 and the cooperating valve chamber on the upper side of the valve land 526. As previously mentioned, the low range valve 526 is effective to control the distribution of control pressure to the high and low speed steering clutches on the left side of the gear assembly of FIG. l, and it is also effective to control the distribution of a modulated uid pressure to the disc brake assemblies 374 and 338. However, for purposes of convenience, only the brake assembly 374 has been illustrated in FIG. 4.

When the manual valve assumes the neutral position illustrated in FIG. 4, control pressure is distributed to the annular space in the manual valve chamber between valve lands 430 and 432 through the aforementioned passage 426 and a passage 532. This control pressure is then conducted through internal passage 442 and through the annular space dened by valve lands 434 and 436 to a passage 534 communicating with the manual valve chamber. Passage 534 extends through a so-called neutral valve, identified in FIG. 4 by numeral 536, to one side of the valve element 506 in the C1 transition valve.

' ahogar/sf passage 426. Communication between passage 558V andV a passage 540 is thereby interrupted. The .passage 541) communicates withvthe C1 transition valve chamber at alocation intermediate Valve lands 562 andSiLlg and'itlalso,k

communicates with the C2 transition yvalve chamber ;,atv a location on the leftrhand side of valve spool 5%. Pas-y f sage 540 also communicates with the C1 clutch through y a passage 542, asindicated.

The neutral valve 536 also establishes communication i between passage 532 and a passage 544,.;the latter extendf,

ing to a uid pressure chamber on the lower side ofthe rst speed synchronizer servo piston 469 and to the C1,V g transition Valve chamberon the left side of thepCl transi- Vtionrvalve spool 560. Communication is also established between'the passagel 546V through the neutral valve 5,36,

her on theV left Vside of valve'element.514. Thevalve andthe passage 546 extends to the transition valve cham.v

spool 5&8 is therebyV urged in a right hand direction, as j viewed in FlG. 4, and valve land 510 is effectiverto block'v passage 548 which extends to the main control pressure:l Y

' v passage 4423. Communication is thereby interrupted be'-` tween passage 548and the Vpassage 55t,"the latter communicating withtheC2 transition valve chamber at a point v In addition, thek manual Valve Aestablishes'fiu'id come` Y munication between passages532 and the passages 554.-

and 556 when'it assumes Vthe neutral position shown in FIG., 4,2passage 554 extending to the pressure chamber onthe upper side of the low range valve 45t; and the pas sage 556 extending to thel pressure chamber` onl the upper side of theflow range valve 456; Control pressure passage 465 communicates, with low range valve 456 ata location Y adjacent valve land522, andrwhenivalve spool 516;,isfin theposition shown, communication is .established between Y passage 46S and the passageg'passage 555 Vin turncom muni'cating with the ypassage v557 through a low range steering'transitiontvalve 558'.r The passage/556 'in turnV communicates With the-low'steering Yclutch 14. In a similar fashion-passage dillcommunicate's with/the -pas sage. 565i through the low range valt/ e455 Whenthe low'Y range'valveAS assumesathe position shown in FIG.4. The passage 56e in turn is adapted to communicate with the passage y562 `throughalow'range steering transition f valve 564, and the passage 562 in turn communicates with ,Y

the low krange steering clutch'16.-

the YC2 clutch through ,a`

The low range steering transition valve 564-includes a valve spoolV Stirharving Va pair of spaced valve lands`568- and 57?. The valve spool 565 is normallyrurgedfin an valve spring. A fluid pressure chamber is located on the upper side of the valve spool 566 within the associatedV valve chamber. f .v Y

' upwarddirection, as Vviewed in FIG. 4,V by YVa transition; Y

lands 574 :and 576. VValve spool 572 isfnormally urged Y' invan'u'pward direction, as viewed in PEG. 4a, by anA associated .transition valve spring, and Va ilu-idA pressure chamber is situate-d on the upper side of the transition-f valve spool 572 within the associated valve chamber.

Ahigh range steering transition valve forrthe high krange steering clutch 18 is shown at 573 andV it includes a'valve spool 58] yslidably disposed in a cooperating Valve icham-V ber. raads sez andrsst land it is normally urgents @downward direction, as viewed in HG. 4a, by an associated Valve VSpool SStLincludes, a pairoflspaced valve Y A high range. transition -valve is alsoprovided for the: high Vrange steering clutchrwasz-shown M1588, and it s' also includes ka valve `spool 5% having Vva fpair.loffsp-afcedl valve Vlan-ds 5921V and 594; Valve jspool 590 is;normallyi urged ina downward directionr'as viewed in'FIG//tjby l transition valve spring. `fly/Iain control Y'pressureV passage 408 communicates With'the transition '.valveV 57S adjacentvalve land 584% -andja passage 5% extends from the highr range steeringclntch -13 to the Vvalve chamber associated location intermediate valvev l with transition valver573 lat a 552 and 584..: Y

an associated s transition valve spring and a. pressurey cham# ber is Vlocatedlin the; valvek chamberfrfor.transitiongvalve' s 585 on .the-lower side of valvej spool 596,1 avs'viewed-inrV Y FIG.' 4. This pressure chamber for Vtlretransition` valve f, 583 communicates vwithlthe valve `cham-ber Ator the transition valve 564at a location adjacent vahfeland*Ssgfpasf` v sage 596 .-beingj provided 4,for this purposeln asimilarr4 fashionthe ypressure cl'ramberl onrtrhe lower side'ovalve spool 53? for'the `transition valveifcommunicates with i Y the valveV chamber,r .forv the transition valve -55Sfat a location adjacentvalve'flandf-Sli, passage'SV Vbeingfpr'o-"Ly vided for this purpose.

age mechanismV V61th,

MainV control pressure passage'rtl. communicates wi'th steeringvalveetstlfat,a location `adjacent?,valve:landftl and a modulated steeringV pressure passage612 communi-V Cates with'pthe valve chamberfor'thesteeringiyalvetii .f at a locationV intermediate valve landslatteind-"603.1 "Pa'sgsage 612 in turn communicates withthe lowrangevalve 45S iat a location adjacent valve land 5.8,`` land,tivhenthe Y `low range-Valvespool 524`assnnres{ i' i y as illustratedinF1314,commiinuition' :isrfestablishedr,VTI

between the lpassage di?. f andthe passage-61,4," the latter communicating ,withVVV the pressure chamber onlthegupper side fof transition valvetspoolfs and with.a'elutchfbrainey Y steering cylinderle The steering cylinder-615 is asso-2 ci-ated with discV brake assemblies-,374 ,and` `3 8S1and Vit 'fin-'1 cludes a brake pistonwhich may benietehanicallylcoupled V to apistonitl ifor a disc'bra'ke master-gcylinder-shown -at.g62, a suitable linkageg'6r22 Vbeinggprovidedlfor"zthisl, Y purpose. V When .piston-6in is moved in alefthand `direc-,`L tion,-as viewed in FG.Q4, y'iluid pressuregisintroducedint y aworking chamber 62d situated @noneV side@ ofthe 'afore-g ff mentioned discvbrake piston 382., Theapassage intercon? nect-ingworking chamber 62,47* with the -master- ,cylinder1 "6 2`@-was previouslyL identiiiedin.v the description of FG; 2 'l by numeral i.lit'fand .this numeral is: `usedpto'` illustrate the,correspondingspassagein FIG.'

Y When theV valve"sp'ool'fSZforA tlieklowrangevalvew 458 vassumestanV upward position, passage 612V is'ln-miglrtVV f. into ,communicati-onwith passage 560 and passage VGiktis, exhausted through therfexhaustport :associated withV they: low rangevalve 458.v The lo'wran'ge l steering transition r Y valve 564 Will then assume an upward.- position under the. fr l inuence. of spring pressure, Aandthe :rnodulatedfsteering pressurein passage 612, will thereforegbeutransrnitted 5 throughipassage Sento. the'y lov/range steeringY clutch 1t?V through 'passage 562' 'and to .thepre'ssure chamber. on the. lower side of; transition valve Y Apairi'of'steering yvalvesis shownat tandf 662 he lformer. being usedtoV controlthe operation,ofthfsteering? Y V'ciutchesfil anduZt anddiscbrakey ,assemblies` f374andf. n 388 and Vthe latter beingadapted tocontrol; the operationfj of the steering`clutches liland, 18-aand1thefdiso brake" assemblies 392f1an'd 394s/ Steeringyalve itlgincludes aV valve spool .694, lhavinga pair of'spacedvalve landssti` and 593,' which,` is slidably received Yina cooperatingvalvevr Y chamber;` Valve Vspooleibt is .adaptedtojbezurged in fa" downward direction, .as ,viewed inV FIG. 4, bymeans of, i

a personally operable steering linkagej'mechanisrn,schef' Y Y maticall-y designated byinumeralslL-anda resilient spring connection Vis provided .between valveispoolrt'andlinlg- Y ownwardiposition- 4spool 59tljthrough passage,...V Y

Y'l`l1iesteering valverttz .forfthe steering; clntchesilandi i 18 and for the disc brake assemblies 392 and 394 also comprises la valve spool 626 having a pair of spaced valve lands 628 and 630. Control pressure passage 426 communicates with the valve chamber for steering valve 602 at a location adjacent valve land 636, and a passage 632 communicates with the steering valve 662 :at a location intermediate valve lands 62S and 631). Passage 632 in turn communicates with a passage 634 through the low range valve 456 when the low range valve spool 516 assumes a downward position, as illustrated in FIG. 4a. Passage 634 in turn .communicates with one side of a clutch-brake steering cylinder 636 which corresponds to the aforementioned steering cylinder 616. A movable piston is situated in steering cylinder 636 and it is mechanically coupled to a piston 638 disposed in a disc brake master cylinder 64d. When the piston 638 is urged in a right hand direction, fluid pressure is transferred to the disc brake assemblies 392 and 394 through the passage 642.

When the low range valve assumes an upward position, as viewed in FIG. 4a, communication is established between passage 632 and passage 554, and the valves 456, 55S and 578 mutually .cooperate in a manner similar to the mode of cooperation between the above described Valves 458, 564 and 588.

The steering valve 662 may be operated by the vehicle operator by means of -a mechanical steering linkage mechanism shown -schematically at 644, and when it is desired to produ-ce a modulated steering pressure in passage 632, the valve spool 626 may be urged in a downward direction by linkage mechanism 644. A suitable resilient spring connection between the valve spool 626 and linkage mechanism 644 is provided for this purpose. The -modulated steering pressure thus produced in passage `632 is transmitted to the lower end of the steering valve 602 so that the steering pressure produced is utilized to oppose the manual eiort applied by the linka-ge mechanism 644. It is t-hus apparent that the magnitude of the modulated steering pressure vmade available to the steering clutches and brake assemblies on the right side lof the transmission assembly is under the direct control ofthe vehicle operator.

In a simil-ar fashion the modulated steering pressure produced by steering valve 690 in passage 612 is conducted to the lower side of the steering valve 606 and utilized to oppose the manual effort applied to the valve spool by linkage mechanism 616. A forward and reverse valve is shown at 646, and it comprises a multiple land valve spool 648 slidably disposed in the cooperating valve chamber. The upper end of the valve chamber for valve 646 communicates with the manual valve 428 through passage 649 at a location adjacent valve land 436. Valve spool 646 is adapted to control the distribution of iuid pressure to either one Iside or the other of a double acting reverse gear synchronizer servo shown at 65d. When the valve spool 648 assumes the position shown in FIG. 4, pressure is distributed to the upper side of the servo 659 thereby urging an associated servo pist-on 652 Vin a downward direction. This causes a shifting movement -of an associated shifter fork 654, thereby effecting a direct drive connection between bevel lgear 83 and gear 164. However, when valve spool 648 assumes a downward position, iluid pressure is conducted to the lower side -of the servo 650 thereby urging piston 652 and shifter fork 654 in an upward direction to provide a driving connection between bevel gear 9@ and gear 104. When one side of the servo 650 is thus pressurized, the opposite side thereof is exhausted through the valve 648.

Description of operation of the transmission control valves of the circuit of FIGS. 4 and 4a The control circuit of FIGS. 4 and 4a is represented schematically, and the various valve elements thereof may be located in a valve body in the transmission housing. For purposes of convenience, the clutch disc assembly 136 and 192 will be referred to as the C1 clutch, the clutch disc assembly 216 and 220 will be referred to as the C2 clutch, the brake assemblies 392 and 394 will be referred to as the B1 brake, the brake assemblies 374 and 388 will be referred to as the B2 brake, the clutch 14 will be referred to as the right low steering clutch, the clutch 16 will be referred to as the left low steering clutch, the clutch 1S will be referred to as the right hi steering clutch, and the clutch 20 will be referred to as the left hi steering clutch.

By preference, the control circuit includes four hydraulic pumps and two of these are driven by the engine and the other two are driven by the power output members. The engine driven pumps will be collectively referred to in the subsequent description as the front pump, and the pumps driven by the power output member will be collectively referred to as the rear pump. One of the engine driven pumps is used for the purpose of scavenging the fluid coupling housing and for circulating the oil in the hydrokinetic circuit through a heat exchanger, and the other is used for supplying transmission control pressure.

The front and rear pumps are arranged so that either the front pump or the rear pump may supply the fluid pressure requirements of the control circuit depending upon the speed ratio in which the transmission is operating and the operating vehicle speed in that ratio. The discharge yside of the front pump is directly connected to the main pressure regulator valve at a location adjacent valve land 414 so that the degree of communication between the discharge side of the front pump and the low pressure exhaust passage 412 is controlled by valve land 414. The pressure is then distributed to main control pressure passage 408 through one way check valve 413. The left side of valve plunger 416 is subjected to the control pressure i-n passage 408 thereby creating a valve biasing force which tends to increase the degree of communication between the discharge side of the front pump and passage 412. This pressure force is opposed by the pressure regulator valve spring force. It is therefore apparent that the pressure regulator valve will assume a balanced condition, and the control pressure in passage 408 will be regulated at a substantially constant value depending upon the calibration of pressure regulator valve.

If it is assumed that the capacity of the rear pump for any given operating speed is less than the capacity of the front pump check valve 420 will assume a closed position and the front pump will supply the entire pressure requirements of the circuit. However, under those conditions in which the capacity of the rear pump is equal to or greater than the capacity of the front pump, the regulator valve spool will assume a new balanced position and valve land 422 will control the degree of communication between passage 463 and the exhaust passage 412, the check valve 418 being closed and the check Valve 420 being opened. A fluid pressure force is also applied to plunger 416 under these conditions to oppose and balance the regulator valve spring force. When the regulator Valve operates in this fashion, the rear pump supplies the entire pressure requirements of the circuit and the front pump operates with a substantially zero head since valve land 414 is moved to a wide open position when regulation takes place at valve land 422. This reduces unnecessary horsepower loss.

Valve land 424 of the regulator valve controls the distribution of fluid pressure to the fluid coupling 12, as indicated. The regulator valve is arranged so that if the operating control pressure is reduced below a desired normal Value, the valve 424 Will completely interrupt the distribution of fluid pressure to the coupling 12. Full control pressure is therefore supplied to the control circuit immediately after the engine has been started and before the coupling is filled, and maximum oil pressure is therefore made available to the Ytransmission clutches'biefore`V theV transmission is conditioned fortorque delivery;

The elements of the control circuit of FIGS. 4 and `4a have jbeenillustrated inthe neutral position. It will be apparent that control pressure'is distributed directly from passage 498 to the manual Valve at a location intermediate Y valve lands 439 and 432.' The position of the manual valve spool'may be controlled, as previously explained, by ymeans of Va driver operated mechanical linkage'lt. When the manual valve assumes the neutral position illus trated in FIG; 4, control pressure isdistributed through passage 442 tovpassageV 53e, the latter extending to the@ right side of valve yelement506 of the C1 transition valve.v

v'Control pressure is also distributed from passage :544

to passage 546 through the neutral valve, and the passage 546 in `turn distributes pressure to the left hand side of Vthe'C2 transition valve element 5M. Control pressure is also distributedbyvthe manual-valve to passage 556' whichvin vturn extends to thel upper end of the low-range valve spool, the latter thereby being urged in a downward direction against the opposing forceV of the low range Vvalve spring. Y

Control pressure is also distributed tothe upper side of Ythe reversek gear synchronizer servoithereby shiftingV the shifter fork 654iV so that the turbine membervv of the lluid coupling will bel positively connected togear 194.,

through gears 8S, 86, '76 and62.

When the, manual valve is in theV neutral position, the:V

C1 transition `valve andthe C2 transition valve are urged in a lefthand direction and in aV right hand direction, re-

spectively, and they C1 clutch and the C2 clutch 'are thereforerboth exhausted through the exhaust port associated with their respective `transition valves. The V,rst speed synchronizer. servo'piston thus assumes a clutching position thereby clutching gear 2% to countershaftlt Although-the lirst speed synchronizerservo is applied, the Y transmission is not conditioned for torque delivery sincez both yof the power output clutchesV C1 and C2 are .disen- Vgaged. Y

I If it is 'now assumed that the manual valve spool is shiftedto aL reverse position in a downward direction,

passage 534vwill become exhausted and lluid pressure will then be ,exhausted from the right sident-the' C1 tran- Y Vsition valve elemen'ttliV TheC1 transition 'valvev spool will therefore assumea right hand position, and passage.V 544) Vwill therefore communicate directly with Vpassage 5358 thereby permitting jcontrol pressure to pass directly to the C1 clutch. The same control pressure is also dis-A tributed through passage 540 to the Vleftside of the C2y transition Valve spool. 1 Y

WhenV the manual valve spool Vassumes the reverse position, valve land43ll'directs fluidpressure through passage, 649-to .the forward and reversey valve Vthereby shifting the Vlatter in a downward direction. Control pressure is therefore distributedrto'the lower end of the reverse gear synchronizer servo and the upper Aend of the servo is simultaneously exhausted. The shifter fork'd is therefore shifted so that` the turbine of coupling'lis connectedto gear 104 through gears 90, 86,75 and 62,' the gear -104 therefore beingrconditioned for yreverse drive operation,V Since the first speed'synchronizer servo vand the C1` clutch are both simultaneously engaged, the. transmissionmechanismis conditioned for torque delivery and a reverse drive is thus accomplished. Itwill beobservedl that the low range valve continues to assume the downward positionvso that control pressure may be distributed therethrough to passage 555 which in turn communicates with :the 10W steering clutches.

If it is now assumed that Ythe manual valve spoolis shiftedin an upward direction through 'the neutral 'position to the rst speed position, lluid pressure distribution to the upper end of the forward and reversevalve will be interrupted and this valve willassume the position shown.

in FIG. 4. The reversegear synchronizer servo will therefore assume the forward drive position previously described: AlsoV passage 5341:willagaink .bey exhausted through the manualvalve, and thisin turnexhausts fluid pressure from the right side; of'gthe VC1 transition valvel elementV Sle.r Fluid pressure-,continues .to begsupplie'd Y Vto thelower end of the iirst speed.SynChrQnZerIseriVo y piston and to the left side of the Cftrvansition valvey spool.

Fluid pressure also continues tobe suppliedto'the upper ends ofy both lof the low rangeirvalves; A"ltis therefore, apparent thatj control pressure .willzbe Vsuppliedj-rto thelow range ystef-:ring clutches and to the,4 C1 clutch 'while'.` M y the remainingclutches are'disengaged. The transmission i mechanism is therefore yconditioriedfor lrst speed operation as previously described. Y

lf it is now. assumed that the manualvalveV spool shifted in an Vupward ,direction to the seond'spe'ed position, control pressure will befdis'tributed through passage v 442 ofthe manual `valve to the .passageextending'tothe lower end ofthe second speed synchronizer servo piston.V

Valve land 430 vwill therefore' block distributionrof fluid pressure to passage Sllfand the'lluid pressure ydistribultion to lthe first-speed synchronizer. piston and totheV` C1 transition valve spoolwillbeinterrupted. vThejrfight` side of the C1 transition Valve :elementftontinues to be exhausted as it is during 2iirstspeed'pperation.

transition valveto urge the same ina left hand direction.-

This establishes communication 'betweenffpassages"5435, and .55@ .thereby energizing the C2 clutch'.V The: llui'd1 pressure on the; left sidef of; the C2 transition valve element 51d is exhaustedl under these conditions since .theV assocratedrpassage Sdfwhich communicates -with (passage Y 544, is exhausted asrpreviojl'sly explained.

Control pressure is also fdis' ibuted throughrzpassage 55? to the right side, ofy thev C1 transition'fvalve spoolto urge the latterin a left handvgdirectionthereby opening l, Y the C1 clutch tor'exhaust. Fluid pressurealso "continues to be Vsupplied to the upper end of thelow rangevalves thereby causing lluidpressure toV kbe'distrie-utedvr to eachV of.' the low steering clutches through theirrespectivey transitionvalves. Sinceithe C'2Qclutch and vrthevseooudr speed synchronizer are, both 'japplied, Vthe'transmissio'n is conditioned for second speed operation,- as-previously explained. Y l Y Y i Y lf the manual valvespool is now-shifted inanjupward .direction to the thirdspeed position,.valve land 436 inter,

rupts the distribution of huid pressure to thezupper'ends or the low rangevalves and fluid 'pressureonfthe lower side of the second speedfsynchronizer servo is exhausted@ through the manual valvreifV However, control pressuresis dlstributed through passageadlz` in the manual valve spool to the upper end offthe'thirdand :lifth speedxsynchronize'r Y servo vthereby shiftingV the latterin-'a downward direction.

Thissarne luid pressure isf:alsotransmittedfto-the upper. end of the nrst speed synchronizerVservopiston so`that f release or the .-rst speed synchronizer lis assured before the third speed synchronizer can beapplied.

The valve .land 482 on theythird and' fifth synchronizer. 'servo pistonfuncovers :the passage extending to the-lir'st. speed synchronizerservo after the'thirdg, andwtifth speed f synchronlzerservo pistonghasshiftedto an applied posif tion so rthat control vpressure'isdistributed to the left end of the.C1 transitionzvalve spool. valve spool is therefore'shiftedin a rightfhand'direction thereby establishing connnunicationbetween.passage'538 Y and passage 540. The C1V clutchis: therefore energized.

and control pressure is again distributedthrough passage l The C1 transition'. Y

2l v position and the C2 clutch is exhausted. Since the third speed synchronizer is engaged and since the C1 clutch is applied, the transmission mechanism is conditioned for third speed operation. It should be noted, however, that the low range Valves will assume an upward position since control pressure is no longer distributed to the upper ends thereof. The low range steering clutcheswill thus become exhausted through the low steering transition valves and through the low range valves, the associated exhaust port being located in the steering valves. Control pressure also is exhausted from the lower ends of the hi steering transition valves and each of these valves assumes a downward position under the influence of then associated valve springs. It is thus apparent that control pressure will be distributed to each of the hi steering clutches during third speed operation.

If the manual valve spool is now shifted to the fourth speed position, control pressure will be exhausted from the upper end ,of the third and fth speed synchronizer servo piston and uid pressure will concurrently be distributed to the upper end of the fourth and sixth speed synchronizer servo piston thereby urging the latter 1n a downward direction to effect engagement of the fourth speed synchronizer. After the fourth and sixth speed synchronizer servo piston assumes an engaged positron, valve land 492 will uncover its associated passage to effect distribution of fluid pressure through the second speed synchronizer servo to the right side of the C2 transition valve spool, the latter thereby being urged 1 n a left hand direction. The C2 clutch is therefore again applied and control pressure is again distributed through passage 55@ to the right side of the C1 transition valve spool. The C1 transition valve spool therefore assumes a left hand position and the C1 clutch is exhausted. Since the hi steering clutch, the C2 clutch and the fourth speed synchronizer are concurrently applied in this fashion, the transmission mechanism is conditioned for fourth speed operation. It should be observed, however, that the control pressure which is distributed to the upper end of the fourth and sixth speed synchronizer servo piston is also distributed to the upper end of the second speed synchronizer servo piston so that disengagement of the second speed synchronizer is assured before the fourth speed synchronizer servo can be engaged.

1f the manual valve spool is moved in an upward direction to the fifth speed position, the upper end of the fourth and sixth speed synchronizer servo piston is exhausted through the manual valve and control pressure is distributed to the lower end of the third and fifth speed synchronizer servo piston, the latter thereby being shifted in an upward 'direction to effect engagement of the fifth speed synchronizer. Since both the third and fifth speed synchronizers are operated by a common double acting synchronizer servo piston, the engagement of the third speed synchronizer is assured before the fth s eed synchronizer can be engaged.

When the third and .fifth speed synchronizer servo piston assumes an engaged position, valve land 484 uncovers its associated passage to effect distribution of control pressure through the first speed synchronizer servo to the left side ofthe C1 transition valve spool. The C1 clutch therefore becomes applied and control pressure is again distributed through passage S40 to the left side of the C2 transition valve spool. The C2 transition valve spool is therefore shifted inV a right hand direction to effect disengagement of the C2 clutch. Since the hi steering clutch, the fifth speed synchronizer and the C1 clutch are conjointly applied in this fashion, the transmission is conditioned for fifth speed operation.

When the manual valve spool is shifted in an upward direction to the sixth speed position, the lower end of the fifth speed synchronizer servo .piston is exhausted through the manual valve and control pressure is distributed to the lowerI end of the fourthand sixth speed synchronizer servo piston, the latter thereby being shifted in an upward direction to effect engagement of the sixth speed synchronizer. Since the fourth and sixth speed synchronizers are both operated by a common double acting servo piston, disengagement of the fourth speed synchronizer is assured before the sixth speed synchronizer can be engaged. After engagement of the sixth speed synchronizer is cornpleted, valve land 474 uncovers its associated passage to effect distribution of control pressure to the right side of the C2 transition valve sp-ool. The C2 transition valve spool is therefore shifted in a left hand direction and the C2 clutch become-s applied. Control pressure is again distributed through passage 550 to the right hand end of the C1 transition valve spool thereby shifting the latter in a left hand direction to effect disengagement of the C1 clutch. Since the hi steering clutch, the C2 clutch and the sixth speed synchronizer are concurrently applied, the transmission is conditioned for sixth speed opera-tion.

The transmission controls thus far described may be readily adapted to provide full range reverse operation by rnaking an appropriate alteration in the forward and reverse valve. lFor example, this valve may be arranged so that it may be shifted to a reverse position and maintained in that position While the manual Valve is shifted through the various speed positions. It is contemplated that a minimum of .altera-tion would be required to incorporate lsuch a full range reverse feature.

The neutral valve shown in FIG. 4 may be operated b means of the linking mechanism 438. According to a preferred arrangement, the mechanism 438 includes a manually operated lever which may be shifted in a fore and aft direction to accomplish the various speed changes, and when it is shifted in a transverse direction, the neutral valve is actuated. It will be apparent from an inspect-ion of FIGS. 4 and 4a that the transmissi-on will be conditioned for neutral whenever the neutral Valve is shifted in a right hand direction since control pressure will be distributed to both the C1 transition valve and the C2 transition valve to maintain the same in their respective exhausted positions regardless of the position of the manual valve spool. It is therefore possible to shift the transmission from neutral directly into any of the several speed ratios.

Operation of the steering control valves of the circuit of FIGS. 4 and 4a As previously pointed out in the above description of the transmission control valves, the low range valves assume a downward position during operation of the transmission in reverse, in neutral and in the first and second speed ratios. The low steering clutches are therefore engaged during operation in reverse and neutral and in the first and second speed ratios while the hi steering clutches are released. This provides a maximum degree of tractive effort. Turning maneuvers can be accomplished under these conditions by employing clutch-brake steering and the steering valves are eective to prov-ide the necessary control. The right hi steering clutch, the right low steer-ing clutch and brake B1 may be independently controlled by steering Valve 602, and the left hi steering clutch, the left low steering clutch and brake B2 may be independently controlled by steering Valve 60). For purposes of this description the steering Valve 660 is illustrated in an applied position and steering valve 602 is illustrated in a fully released position.

Referring to FIG. 4, the steering valve spool 604 may be depressed by manuallyroperated linkage mechanism 610 so that valve land 668 will provide controlled communication between passage 408 and passage 612. The resulting modulated pressure in passage 612 is conducted to the lower end of steering valve spool 604 thereby creating a pressure force which opposes and balances the steering valve spring force. The magnitude of the modulated pressure in passage 612 can therefore be controlled by the operator by appropriately positioning the steering linkage mechanism,

VIclutches are released.

. released positions Vof device.

2.:In a control system for a powerftransmission mecha,

the loW range valve during yoperation in reverse, neutral,`

rst speed and second speed to the upper end of the low speed transition valve 564.( VWhen the modulated pres.-Y

sure is of a sufficient magnitude,low steering transition VVvalve spool 566 assumes a downward.position-thereby exhausting the lowsteering clutch.' Themodulated steering pressure is applied to the clutch-brake steering cylinder 616 and this applies a disc braking force to the disc brake Y B2 in the manner previously described. Y

If the steering valve 602 'continues to assume vthe posi- Ytion shown inV FIG. 4a, the ri-ght low steering clutch will remain applied.Y The turning radius can be controlled by theivehicle operator merely b y controlling the position lofthe steering valvespool 694, and a large variety of turning radii may be produced. For example, a full pivot turn or avery gradual turnmay be accomplished depending upon the magnitude of the steering pressure' which Sis made'available to brake B2.

' It will, of course, be understood that theV steering valve' 6924 may oper-ate in a manner similar to the .above described operation of steering valve 600 t-o eiect clutchbrake steering in the other direction. Y

. If the transmission vmechanism is voperating in},'third, fourth, fifth, or'sixthispeeds, the low range valve Vwill assume an upward position, as previously described, Vand the hi steeringclutches-,are engaged while the low-steering steering valve -is operated inthe fashion ypreviously de passage 612 or passage 632.

If it is desired to accomplish a turning maneuver under these condition-S, the appropriate Iflit Vis Vassumed that steering valve vspool 626jis def i Y pressed by the vehicle operator, a modulated ksteeringpres-` sure will be-distributed.through the rlowsteering transition valve to the lower end of theh-i speed transition valve. When the modulated pressure is of a suicient magnitude,V n

the hi steeringvtransition valve spool 58d will assume an upward position thereby causing theV right hi steering clutch to become exhausted through the hi steer-ing transition'valve 57S while control pressure distribution to the right hi steering clutch is interrupted.` The modulatedY `steering pressure is distributed through the low steering transition valve 558 to the right low steering clutch thereby causing theV associated track or traction wheel to oper- Y ate at a slower 4speed than the track or traction wheel on the opposite side of the vehicle. The vehicle will therefore/turn with a predetermined turning radius depending e upon the relative gear ratios associated with the torque de- Y f livery paths through the hi andlow steering clutches. e

Having thusV described a preferred embodiment ofz our invention-what we claim and desire to secure `by United 1 States Letters Patent is:

1. In a control system for a power transmission mechanism having engageable and Vreleasable torque transmitting devices, separate fluid pressure operated Yservos adapted toactuate each device, a iluid pressureV source,

conduit structure including separateY portionseXtending respectively from said'source to each of saidservos, rst

valve means disposed in and partly defining lthe conduitV structure portion for one of said servos for distributing pressure to said one servo and 'exhausting thesame,V` a;

Y signal `.pressure passage communicating with said first valve means and with a high pressure region of said con-` duit structure, second valve means disposed in and 'partlyV defining said signal pressure passage,vsaid second valve means having movable portions connected to movable parts of anotherV of said servos, the firstvalve means responding to a change in pressure in said other servo witha delayed action as pressurein said signal pressure iscontrolled upon movement 4of said-other Vservo between two positions corresponding respectively to engaged and its kassociated torque transmitting valve means disposedin and partly Adefining theilconduit structureY portionl forone foffsaid servos orfdistributing -15 pressure to saidone servo and exhausting the. same,fak Y signal pressure passage communicating with fsaid irsjtV n valve means and Withda highf'pressurejregion ofgsaidkg conduit structureg; second valve meansdisposed in and partly defining said vsignal ,pressurefpassagd said gsec'- ond valve 'means havingmovable VVportions connected.V 'Y to movablepartsof vanother servo, distributionfof' pres'- Y sure Vto. saidfsignal pressurfeypassagef being V'controlled by ysaid other servo upon movement thereof between two 'c t positions corresponding Vrespectively to.,Y engaged 'andreleased positions of its associated torque transmitting device, -Y said otherlservo being double-acting andmovable toeach -5 of said positions, said r'stvalvemeans'for-:said one 'servo Y responding .to ga pressure 'buildup 'inthegotherVservoforf controlling movement Yof said one :servoV to a device re-Y leasing positionfwhereby'actuation of said "one servo is` y delayed until the otherservo-hasassumed-'a disengaged n position.v 3. Ina control communication whereby lorie of themis urgedjto `a device releasing; position as the gaging position.

conduit f structure includingY separate portions. extending respectively Vfrom said; source tojeach-of `saidv servos,V firstvalve means disposed in and partlydeining the conduit.V structure: portion `for one of `said servos for distributingf pressure ,to` said -one servo and Vexhausting Vthefsarne, fa signal pressure passage pcommunicating with said firstI valve means vand-,with a'high pressureregion sofffsaid conf747V duit structure, second lvalverneans-disposed Vin, andpartly y Ydeiining vsaid vsignal` pressure passage,'said second, valve means: having movable-portions fconnected-togrnevable parts Yof another servo `of saidseparateuservQS, theitirst. Y valve means respondingto Yachange,ingpressure in said'v Y "other servo :with a delayed Yaction-as pressuregin said signal pressure passage fis controlle'd'upon .movementoff 'said i otherservo 'betweenf two' positions corresponding respeef'ztivelyto engaged andreleased positions `oflits `associated. f f ,l torque transmitting.device, -andpersonally,operableaselec-r Y tor valve mea-risAY situatedin and partlygdeiininga-portion@ of said conduit structure `betweensaid pressure source, and said otherservo whereby pressure vcan be: distributed selectively to said other-servo byap'propriately manipulat- `ing said manual valve means.- .i n 5.1;Y In a controly system fora Vpower transmission mech-v system for alp'owentransmission mech-y anism; vhaving engageable and releasable torque, trans-f, mitting devices?? separate iiuid pressure operated servosv Y Vadapted to l actuate 'each '.device, 1 a iuicl `pressure source, conduit, structure','including'l separateportions@extendingf Y respectivelyrfromsaid sourceto each of said'servos of said. system, valve means disposed `ir'randffpartly,defining the.y if onduitfstructure portion for ,onegof'said'fser-vos' for. dise Y tributing pressure to said-.one servo ,andgjexhausting the same,yandV a signal'pressure passage communieating with said valve Vrneansand with alhighpressureregioni'ofjsaidV conduit'structure, said valve means respondingtoa changel in pressure in anotherservo vwith a delayed-,action fas pres,- ...f

sure in saidzfsigna'lV pressurevpassage is controlled Vupon;V j movement ofsaid other-servo-zbetweentwo positionsA cor- Y responding, respectively-to engaged'and-ieleased positions Yof itsA associated torque transmitting device, said other servo and a .third of said servosin said systemehayingfpor-f tions disposed in and partly dening saidrsignal pressure'.rvr passage, said other servo and'said'third servo beingin iiuid"` other 'is urged tto its device enanism having engageable and releasable torque transmitting devices, separate uid pressure operated servos adapted to actuate each device, a fluid pressure source, conduit structure including separate portions extending respectively from said source to each of said servos, first valve means disposed in and partly defining the conduit structure portion for one of said servos for distributing pressure to said one servo and exhausting the same, a signal pressure passage communicating with said first valve means and with a high pressure region of said conduit structure, second valve means disposed in and partly dening said signal pressure passage, said second valve means having movable portions connected to movable parts of another servo of said separate servos, the irst valve means responding to a change in pressure in said other servo with a delayed action as pressure in said signal pressure passage is controlled upon movement of said other servo between two positions corresponding respectively to engaged and released positions of its associated torque transmitting device, said other servo being double-acting and movable in each of said directions, said first valve means for said one servo responding to a pressure build up in said other servo for controlling movement of said one servo to a device releasing position, and personally operable selector valve means situated in and partly dening a portion of said conduit structure between said pressure source and said other servo whereby pressure can be distributed selectively to said other servo by appropriately manipulating said manual valve means.

6. In a control system for a power transmission mechanism having engageable and releasable torque transmitting devices, separate fluid pressure operated servos adapted to actuate each device, :a Huid pressure source, conduit structure including separate portions extending respectively from said source to each of said servos, rst valve means disposed in and partly defining the conduit structure portion for one of said servos for distributing pressure to said one servo and exhausting the same, a signal pressure passage communicating with said rst valve means and with a high pressure region oi said conduit structure, said rst valve means responding to a change in pressure in another of said separate servos in said system with a delayed action as pressure in said signal pressure passage is controlled upon movement of said other servo between two positions corresponding respectively to engaged and released positions of its associated torque transmitting device, said other servo and a third servo of said separate servos in said system having portions disposed in and partly dening said signal pressure passage, said other servo and said third servo being in uid communication whereby one of them is urged to a device releasing position as the other is urged to its device engaging position, and personally operable selector valve means situated in and partly defining a portion of said conduit structure between said pressure source and both said other servo and said third servo whereby pressure can be distributed selectively to said other servo and said third servo by appropriately manipulating said manual valve means.

References Cited by the Examiner UNITED STATES PATENTS 1,646,552 10/27 Mosel.

2,600,043 6/52 Armitage et al. 192-87 2,703,638 3/55 Super 192-87 2,824,632 2/58 Lucia et al 192-3.2 2,958,231 11/ 60 Gerst.

3,044,318 7 62 Hardman.

3,059,740 10/ 62 Roche 192-3.2 3,059,746 10/62 Christenson 192--87 3,144,107 8/64 Davies et al.

DAVID J. WILLIAMOWSKY, Primary Examiner.

DON A. WAITE, Examiner. 

1. IN A CONTROL SYSTEM FOR A POWER TRANSMISSION MECHANISM HAVING ENGAGEABLE AND RELEASABLE TORQUE TRANSMITTING DEVICES, SEPARATE FLUID PRESSURE OPERATED SERVOS ADAPTED TO ACTUATE EACH DEVICE, A FLUID PRESSURE SOURCE, CONDUIT STRUCTURE INCLUDING SEPARATE PORTIONS EXTENDING RESPECTIVELY FROM SAID SOURCE TO EACH OF SAID SERVOS, FIRST VALVE MEANS DISPOSED IN AND PARTLY DEFINING THE CONDUIT STRUCTURE PORTION FOR ONE OF SAID SERVOS FOR DISTRIBUTING PRESSURE TO SAID ONE SERVO AND EXHAUSTING THE SAME, A SIGNAL PRESSURE PASSAGE COMMUNICATING WITH SAID FIRST VALVE MEANS AND WITH A HIGH PRESSURE REGION OF SAID CONDUIT STRUCTURE, SECOND VALVE MEANS DISPOSED IN AND PARTLY DEFINING SAID SIGNAL PRESSURE PASSAGE, SAID SECOND VALVE MEANS HAVING MOVABLE PORTIONS CONNECTED TO MOVABLE PART OF ANOTHER OF SAID SERVOS, THE FIRST VALVE MEANS RESPONDING TO A CHANGE IN PRESSURE IN SAID OTHER SERVO 